平衡搜索二叉树实现
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public class BBST<Key extends Comparable<Key>, Value> { private Node root; public class Node { private Key key; private Value val; private Node parent, left, right; private int height; private int bfc; //balance factor private Node(Key key, Value val, int height, Node parent, int bfc) { this.key = key; this.val = val; this.height = height; this.parent = parent; this.left = this.right = null; this.bfc = bfc; } } public Value Search(Key key) { return SearchIn(root, key); } private Value SearchIn(Node t, Key key) { if (t == null) return null; else if (key.compareTo(t.key) == 0) return t.val; return SearchIn(key.compareTo(t.key) < 0 ? t.left : t.right, key); } private void connect34(Node a, Node b, Node c, Node t0, Node t1, Node t2, Node t3) { b.left = a; b.right = c; a.parent = b; c.parent = b; a.left = t0; if (t0 != null) t0.parent = a; a.right = t1; if (t1 != null) t1.parent = a; c.left = t2; if (t2 != null) t2.parent = c; c.right = t3; if (t3 != null) t3.parent = c; root = b; } private void UpdateHeight_BFC(Node x) { Node x2 = x; while (true) { if (x.left == null && x.right == null) { x.height = 0; x.bfc = 0; } else if (x.left == null) x.height = x.right.height + 1; else if (x.right == null) { x.height = x.left.height + 1; System.out.println(" "); } else x.height = (x.left.height == x.right.height ? x.left.height : x.left.height > x.right.height ? x.left.height : x.right.height) + 1; if (x.parent == null) break; else x = x.parent; } while (x2 != null) { if (x2.left == null && x2.right == null) { } else if (x2.left == null) x2.bfc = 0 - x2.height; else if (x2.right == null) x2.bfc = x2.height; else { x2.bfc = x2.left.height - x2.right.height; } x2 = x2.parent; } root = x; } private boolean Balanced(Node t) { return t.bfc < 2 && t.bfc > -2; } private void ReBalance(Node t) { while (t != null) { if (!Balanced(t)) { Node son = null, grandson = null; if (t.bfc > 1) { //左子树不平衡 son = t.left; if (son.bfc < 0) { //左右 if (t.parent != null) { if (t.parent.left != null && t.parent.left.key == t.key) t.parent.left = son.right; else t.parent.right = son.right; son.right.parent = t.parent; } son.right.parent = null; connect34(son, son.right, t, son.left, son.right.left, son.right.right, t.right); UpdateHeight_BFC(t); UpdateHeight_BFC(son); break; } else { //左左 if (t.parent != null) { if (t.parent.left != null && t.parent.left.key == t.key) t.parent.left = son; else t.parent.right = son; son.parent = t.parent; } son.parent = null; connect34(son.left, son, t, son.left.left, son.left.right, son.right, t.right); UpdateHeight_BFC(t); UpdateHeight_BFC(son.left); break; } } else { //右子树不平衡 son = t.right; if (son.bfc < 0) { //右右 if (t.parent != null) { if (t.parent.left != null && t.parent.left.key == t.key) t.parent.left = son; else t.parent.right = son.left; son.parent = t.parent; } son.parent = null; connect34(t, son, son.right, t.left, son.left, son.right.left, son.right.right); UpdateHeight_BFC(t); UpdateHeight_BFC(son.right); break; } else { //右左 if (t.parent != null) { if (t.parent.left != null && t.parent.left.key == t.key) t.parent.left = son.left; else t.parent.right = son.left; son.left.parent = t.parent; } son.left.parent = null; connect34(t, son.left, son, t.left, son.left.left, son.left.right, son.right); UpdateHeight_BFC(t); UpdateHeight_BFC(son); break; } } } t = t.parent; } } public void Insert(Key key, Value val) { if (root == null) { root = new Node(key, val, 0, null, 0); return; } Node temp = root; while (true) { int cmp = key.compareTo(temp.key); if (cmp < 0) { if (temp.left == null) { temp.left = new Node(key, val, 0, temp, 0); UpdateHeight_BFC(temp); ReBalance(temp); return; } else temp = temp.left; } else if (cmp > 0) { if (temp.right == null) { temp.right = new Node(key, val, 0, temp, 0); UpdateHeight_BFC(temp); ReBalance(temp); return; } else temp = temp.right; } else { temp.val = val; return; } } } public void Remove(Key key) { Node temp_root = root; if (root == null || key == null) return; while (temp_root != null) { int cmp = key.compareTo(temp_root.key); if (cmp > 0) temp_root = temp_root.right; else if (cmp < 0) temp_root = temp_root.left; else { if (temp_root.left == null || temp_root.right == null) { if (temp_root.left != null) { temp_root.key = temp_root.left.key; temp_root.val = temp_root.left.val; temp_root.left = temp_root.left.left; temp_root.right = temp_root.left.right; } else if (temp_root.right != null) { System.out.println(" "); temp_root.key = temp_root.right.key; temp_root.val = temp_root.right.val; temp_root.left = temp_root.right.left; temp_root.right = temp_root.right.right; } else { temp_root = temp_root.parent; if (temp_root.left != null && temp_root.left.key == key) temp_root.left = null; else temp_root.right = null; } UpdateHeight_BFC(temp_root); ReBalance(temp_root); } else { Node t = temp_root.right; while (t.left != null) t = t.left; temp_root.key = t.key; temp_root.val = t.val; if (t.right != null) { t.key = t.right.key; t.val = t.right.val; t.left = t.right.left; t.right = t.right.right; } else { t.parent.left = null; } UpdateHeight_BFC(t); ReBalance(t); } } } } public static void main(String args[]) { BBST<Integer, Integer> t = new BBST<Integer, Integer>(); t.Insert(50, 1); t.Insert(60, 4); t.Insert(40, 2); t.Insert(30, 3); t.Remove(60); System.out.println("断点设置处"); } }
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